System and apparatus for automatic wave selection



J. H. HAMMOND, JR;

SYSTEM AND APPARATUS FOR AUTOMATIC WAVE SELECTION.

APPLICATION FILED JAN. 21, I910. RENEWED DEC. 7, 191B- 2 SHEETS-SHEET l- Patented J 11110 20, 1922.

i:: Lil Q I. H. HAMMOND, JR.

SYSTEM AND APPARATUS FOR AUTOMATIC WAVE SELECTION.

APPLICATION FILED JAN- 2|, I9I0. RENEWED DEC.7,1918.

l ,%2@,257u Patented June 20, 1922.

2 SHEETS-SHEET 2.

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SYSTEM AND AIPPARATUS FOR AUTOMATIC WAVE SELECTIOliT.

Specification of Letters Patent. P tent d J n 2 1)) 1922,

Application filed January 21, 1910, Serial No. 539,248. Renewed December 7, 1918. Serial No. 265,787. I

To all whom it may concern:

Be it known that I, J OHN HAYS HAMMOND, Jr, a citizen of the United States, residing at Gloucester, in the State of Massachusetts, have invented certain new and useful Improvements in Systems and Apparatus for Automatic WVave Selection, of which the following is a specification, reference being bad to the accompanying drawings, forming a part hereof.

In transmitting wireless messages interferences of different messages often occur when two independent operators send their messages by chance in the same wave length.

Vhen this occurs the message being received becomes unintelligible as the two messages become mixed together. invention is to provide means whereby a message may be sent in impulses of different predetermined wave length succeed- ]ing each other in a predetermined order.

Thereceiving instrument is arranged so that it is rendered responsive successively to the different wave lengths in the same predetermined order. In this way a message which .passes between the operators is composed of elements constantly changing in wave length. Hence it becomes impossible for an operator of another instrument to interfere of the receiving station.-

Fig. 5 is a view of the compensator magnet in its operative position.

Fig. 6 is a view of the same in its nonoperative position.

The alternating current generator or other suitable source of power 1 is in primary circuit with a low frequency transformer 2.

A spark gap 41 is connected in shunt with the left hand or secondary winding of the transformer-2. A key 3 is also in the circuit. The current passes through a condenser 4 and. thence to the high frequency oscillatory transformer 5 having a plurality of contacts The object of this 6 corresponding to the different wave lengths, the waves being propagated through the aerial 7. The transformer is rotated by a solenoid 8 in circuit with the generator or primary circuit, having a shifting corerod 9 operatively connected to the transformer witha suitable pawl and ratchet arrangement 10 which permits the rod to return to its initial position under the influence of the spring 11 when the circuit is broken by the key 3. A suitable brake or other re sistance 12 is connected with the core-rod to regulate and determine the movement of the same as hereinafter described.

The receiving station is provided with an aerial 14 connected with a suitable tuning coil 15 provided with a plurality of contacts 16 corresponding to the contacts upon the transformer 5. Said coil is in circuit with a coherer v17 connected with a relay 18 through a battery or cells 19. The armature 20 of the relay controls a switch in the circuit comprising the main battery 21 and a solenoid 22 provided with a movable corerod or traveller 23. This core-rod is operatively connected with the coil 15 through a pawl and ratchet 24 of any well known 0011-.

struction which permits the rod to return to its initial or starting position under the influence of the spring 25 as soon as the solenoid ceases to be energized.

A. brake or retarder 26 is connected to the rod 23, which is preferably similar inconstruction to the brake or retarder 12 connected with the transformer 5. Said brake comprises a cylinder adapted to contain oil, water or other liquid and having a piston or plunger 27 movable therein which is mounted on or secured to the rod 23 in any suitable manner. A by-pa'ss 28 controlled by a valve 29. extends from one end of the cylinder to the other, thus permitting theliquid to flow from one side of the piston to the other as the piston is operated, the said valve providing a sufiiciently delicate means for controlling the rate of flow of the liquid from one side of the piston to the other and consequently the speed of the solenoid.

In order to insure the proper working of the receiving station and to compensate for any differences which may arise in the o eration of the solenoids and therefore in t e rates of rotation of the'transformer and the tuning coil a device is provided which I designate as a compensator. Said device comprises a contact finger or brush 30 mounted upon the core-rod of the solenoid 22 and adapted to engage with contacts 31 and 31 in local circuit with the battery 32. Said contacts are arranged so that the finger 30 engages therewith shortly prior to the instant when the contacts on the tuning 0011 are changed, thus insuring such change and that the tuning coil will again be brought into unison with the transformer although the rates of rotation of the transformer and tuning coil may not be absolutely uniform. One of such contacts is provided for each change in the wave length and the contacts are arranged with a suitable space between same corresponding to the major portion of the next succeeding contact on the tuning coil. A contact 33 is also provided which closes the circuit through any suitable operating mechanism or apparatus, such as S'. In order to control the contact finger 30 a local'magnet 35 is provided in circuit with the main battery having its armature operatively connected with said finger by a lever 36. As soon as the, relay 18 is energized the current through said magnet is, automatically closed and the contact finger is caused to engage with the contacts 31. As soon as the circuit is broken, however, the contact finger is held'out of engagement by any suitable means as a spring 37.

In operation the transformer or other inductlve means at the sending station is ar-.

ranged in its initial position to propagate;

waves of a given length, such for example as 200 yards and the tuning coil or other adjustable inductance at the receiving station is arranged so that its inductance will be receptive to said wave lengths. Upon closing the sending circuit, an impulse of this wave length is propagated, which is received by the receiving station, and the solenoid 22 is energized through the relay 18, which operates the tuning coil and also brings the finger 30 into contact with one of the contacts as 31*. Thus an independent local circuit with the solenoid and the battery 32 is established, which causes the solenoid to be energized and the core rod to travel until the finger has .been disengaged from the contact 31; this rotates the tuning coil sufliciently to bring the next contacts 113 under their brushes, and cause the corresponding inductance of the tuning coil to be substituted in series with the aerial 14, whereupon the aerial circuit will-be responsive to the next pre-determined successive wave length,- as for instance waves of 400 yards. Meanwhile the'length of the'waves propagated from the sending station has been changed in any suitable manner to the next pre-determined succeeding wave length, preferably automatically. as shown byproviding a solenoid 8 in circuit with the pri mary of the transformer 01 other variable inductance, although it is obvious that the variable inductance may be operated manually if desired. Consequently as soon as the receiving circuit becomes responsive to the said wave length the solenoid 22 is again energized by the circuit comprising the relay l8, and the core rod is thus caused to travel on again in the same direction until the contact finger 30 contacts with the contact 31 of the compensator, which will re-establish a local circuit with the battery 32 and cause continued rotation of the tuning coil or other suitable inductance until it is synchronized or, brought to resonance with the next pre-determined succeeding wave length. Thereupon the length of the waves propagated from the sending station is again changed according to the pre-determined'sequence which again closes the circuit comprising the relay 18, energizin the solenoid or other operating means an carrying the contact finger 30 into engagement with the contact 33. This establishes a circuit that will perform any desired work, such as the 3 operation of a motor or even operates as a sounder to convey the signals of a telegraphic code.' This circuit will be established as long as the key 3 is closed and when the key 3 is opened the traveller 23 will. move to the right, thus opening said circuit and placing the apparatus in its initial position. In addition to the foregoing essential elements and operations embodying my invention,,'I may if, desired provide a brake'or retarder 26'as a further and additional precaution against"interference. The fuse of this brake or retarder introduces the element of'time into the operation of the mechanism, since an appreciable interval of time is required for the liquid to pass from one'side of the piston to the other, and consequently it is necessary, in order to establish connection with the contact 33 and perform the desired work, to propagate the Waves not only in proper sequence, but also at the proper time intervals. Preferably a similar brake or retarder 12 is used at the sending station, although, as above noted, it is not essential to my invention that the inductance of the sending station be changed automatically, as it is obvious that it can be changed manually at predetermined intervals. It is evident, however, that the brake. orv retarder will be used only when the'apparatus is used tocontrol mechanism or when it is especially desirable to introduce a time element, and that the brake or retarder will not be used in the ordinary transmission of intelligible signals.

When, as above described, electric waves are first sent from the transmitting station, the oscillatory transformer 5 and'the tuning coil 15 at the receiving station, are in such positions that the transmitting and 'receiving circuits will be in tune with each iii-$20,25

other. The contact piece or finger 30, at= tached to the core-rod 23, is then at the right of contact 31. This contact finger 30 has its upper and lower ends insulated from each other, its lower end being adapted to contact with the contacts 31 and 31", and its upper end being adapted to contact with the contact 33, and being electrically connected with the mechanism or apparatus S.

When the transmitted electric waves are received on the tuned antenna circuit 14, 15, 17, the relay 18 is energized, the armature 20 is attracted and completes a circuit through the battery 21 which includes the solenoid 22 and the magnet 35.

Solenoid 22, being energized, attracts corerod 23 and draws it, together with contact finger 30, to the left, and at the same time the pawl and ratchet 24 turns tuning coil "15 so that the wavelength of the receiving antenna circuit is changed. Simultaneously, at the transmitting station, the oscillating transformer 5 is being turned by means of the solenoid 8, core-rod 9 and pawl and ratchet 10 so that the wave length of the transmitting antenna circuit will correspond with that of the receiving antenna circuit. During this process of changing the wave length of both circuits, there may be a period when the circuits will not be in tune, and when, consequently, relay 18 will not be energized and the circuit including battery 21, solenoid 22 and magnet 35 will be interrupted. During-this period, then, the corerod 23 and contact finger 30 would return to their original position if some other means were not provided to keep them moving to the left. In order to keep solenoid 22 and magnet 35 energized during this period, I have provided the contact 31?, battery 32 and a local circuit through solenoid.

22 and magnet 35, which will make sure that the corerod 23 will continue to move to the left during the period of change in the tuned transmitting and receiving circuits.

\Vhen the contact finger 30 has passed beyond 31 to the left, the transmitting and receiving circuit will again be in tune',lout with a new wave length, and the relay 18 will be energized and the circuit. containing the battery 21, the solenoid 22 and magnet 35 will be completed. Contact 31 is provided so that if there is another change in the wave length and another period when the transmitting and receiving circuits are out of tune, the solenoid 22 and magnet 35 will continue to be energized. In this way, I make sure that as long as the key 3 is closed and electric waves are sent out from the transmitting station, the core-rod 23 will keep on moving to the left until the upper end of contact finger 30 touches contact 33,

and so causes mechanism or apparatus S to be actuated.

The retarderr or clash-pots 12 and 26 are element for the purpose of making my system still more selective, but when messages are to be sent quickly, these retarders should preferably be omitted.

During all this time, the magnet is energized and by suitable means causes the contact finger 30 to remain in a position to make contact with 31, 31 and 33, but whenever the key 3 is opened and the propagationof waves at the sending station is interrupted or stopped, the magnet 35 will be de-energized and the contact finger 30 will be moved into a position where it can no longer contact with 31, 31 or, 33. At the same time, the solenoid 22 will be de-energized, and the spring 25 will cause the corerod 23 to be returned to its original position. During this movement of core-rod 23 to the right, the finger 30 will be held out of the path of contacts 31 and 31*, by means controlled bythe magnet 35, as above described, and the local circuit containing battery 32 will not be established. Instead of this magnet 35, however, I' may employ other electrical or mechanical devices to hold the contact-finger out of contact with the other contacts during the return movement of the core-rod'or traveler 23.

It will be obvious that innumerable combinations may be made and that the wave lengths employed and the order and duration of each train of waves of a given length may be varied at will. It is obvious also that the invention is not limited to the particular form of mechanism shown and described herein, as any suitable variable inductance or capacity may be substituted for the transformer and tuning coil at the sending station, and the receiving station re described without departing from the spirit 'of the invention, provided the means set forth in the following claims'be employed.

I claim as my invention: 1. In a system of automatic wave selection the comblnatlon of a transformer at the sending station, a rotatable tuning coil at the receiving station, means for operating the transformer to change the wave lengths at pre-determined intervals, means to rotate said tuning coil in approximate synchronism with the transformer, and means for compensating any variation in the rate of rotation of said transformer and tuning coil. g

3. In a system of automatic wave selection, the combination of a transformer, a

5 solenoid operatively connected with said transformer to rotate same and change the lengths of the waves propagated thereby at pre-determined periods, a rotatable tunin coil, and a solenoid operatively connecte with said tuning coil to rotate same in approximate former. V

- 4. In a system of automatic wave selection, the combination of a rotatable transsynchronism with the transformer, a solenoid operatively connected with said transformer to rotate same to change the wave lengths of the impulses propagated thereby, a rotatable tuning coil, a solenoid for rotating said tuning coil in 0 approximate synchronism with the transformer and a compensator comprising contacts in a local circuit arranged to regulate the action of said solenoid at pre-determined intervals to maintain synchronism between 5 the said transformer and said tuning coil.

5. In a system of automatic wave selection, the combination of a rotatable trans former, means for rotating said transformer to vary the wave lengths of the impulses 0 propagated thereby, a rotatable tuning coil,

means for rotating said tuning coil in approximate synchronism with the transformer, and means for automatically returning the transformer and the tuning coil 5 to their initial positions when the generating current is interrupted.

6. In a, system of automatic wave selection, a sending station comprising means for propagating waves having different 0 frequencies in succession and a receiving i sating-for variations in synchrony between the sending and receiving stations.

8. In a system of automatic wave selection, a sending station comprising means for propagating waves of different periodicity in a predetermined order of succession, a receiving station comprising a receiving de vice having a movable member operatively secured thereto to adapt said receiving device to receive said waves in the predetermined order of succession, andmeans enermacaw able member whereby said receiving device is successively placed in resonance with the sending station.

9. A system of automatic wave selection comprising a sending station having means for propagating waves of predetermined periodicity in a predetermined order of succession, a receiving station comprising means adapted to receive the waves propagated from the sending station, movable means operatively connected with said. receiving means to automatically actuate same to receive the waves propagated in a predetermined order of succession, and a local circuit independent of the sending station comprising means to actuate said receiving means automatically.

10. A system of automatic wave selection comprising a sending station having means for propagating waves of predetermined periodicity in a predetermined order of succession, a receiving station comprising means adapted to receive the waves propagated from the sending station, a local circuit adapted to produce intelligible signals, a traveler operatively secured to the receiving means, a brush carried by said traveler to close said local circuit and means for actuating said traveler whereby waves of a plurality of periodicities are required to close said local circuit.

11. In a system of automatic wave selection a sending station comprising means for propagating waves of different periodicities in predetermined order of succession, a receiving station comprising means adapted to receive waves of different periodicities, a moving partoperatively connected with said receiving means to adapt same'to receive the propagated waves in the proper order of succession, meansfor actuating said moving part normally energized by a circuit controlledby said receiving means, an independent local circuit for energizing said actuating means, and a contact carried by said moving part for closing said local circuit when the condition of receptivity of the receiving means is changed.

'12. A system of automatic wave selection comprising a sending station having a variable inductance arranged so as to be automatically changed to propagate electromagnetic waves of differing periodicity and of predetermined order of succession and duration, a receiving station comprising a receiving circuit and means for changing the inductance in the receiving circuit, which means shall be operated by the said sending station, so that the said inductance in the receiving circuit shall cause the said receiving circuit to be receptive to waves of predetermined periodicity succession and time interval as emitted by the seiidlng station.

propagating electrical vibrations successively varying in frequency, and a receiving station including a plurality of elements successively energized in response to said successively varying vibrations and a device 20 responding to said transmission means onlyas the result 'of the successive energization of a plurality of said elements.

TlllS specification signed and witnessed this 18th day of January, A. D., 1910.

JOHN HAYS HAMMOND, JR. Signed in the presence of N. A. SMITH, AMBROSE L. OSHEA. 

